EFFECTS OF RARE SUGARS ON GROWTH AND DISEASE OCCURRENCE IN HEAD LETTUCE

The International Society of Rare Sugars (ISRS) defines rare sugars as mono-saccharides and their derivatives that rarely exist in nature. D-Psicose and D-allose are typical rare sugars and are expected to be used as a functional sweetener and in medical products, respectively. Only a few genetic studies have been performed for elucidating the elicitor activity by which D-psicose and D-allose induce disease resistance. Further, D-psicose and D-allose are known to be able to control the growth of rice plants. The purpose of our investigation was to determine the advantages of using rare sugars as fertilizers or agricultural chemicals for plants cultivated in hydroponics. In this study, we examined the effects of rare sugars, especially D-psicose and D-allose, on the growth of and disease occurrence in head lettuce cultivated in a nutrient solution culture. D-Psicose and D-allose were suggested to be used as regulators of plant growth in the case of plants cultivated in hydroponics. The growth and development of head lettuce cultivated in hydroponics was dependent on the concentrations of D-psicose or D-allose. Furthermore, D-psicose and D-allose induced disease resistance and prevented the occurrence of disease in head lettuce.